Can a hydraulic pump push fluid

2025-08-20

The hydraulic pump converts the mechanical energy of the prime mover into hydraulic energy for use by the system. Hydraulic energy is a combination of pressure and flow required for the actuator to perform useful work. It is important to understand that hydraulic energy is both pressure and flow, as one cannot accomplish work without the other. Pressure consists of stagnant fluid, and flow would have no energy to move the fluid alone.

The hydraulic pump propels fluid, and in this context, the fluid can be regarded as a solid, as it travels throughout the machine and then drives the actuator to move the load. Motion control experts would point out that oil is compressible, but that's a discussion for another blog.

The key point is that the pump may push on sand, ball bearings, or other solid media that can form the shape of its container, and the result is still the transmission of force.

The transmission of force is indeed synonymous with hydraulics and forms the basis of the Kosford's Law, which states that "pressure makes it disappear, and flow rate is the rate at which pressure can be generated." Regarding the motion of fluid, pressure reaches the pump position; always. Faced with the fallacy that pressure is against flow, this is incorrect. Pressure will rise to the pressure required to overcome downstream resistance, but if the pressure is not initiated at the pump, the fluid will move backwards.

The pressure in hydraulic systems is a result of Newton's third law of motion, which states that every action has an equal and opposite reaction. The reaction force can be provided by a loaded cylinder or a flow controller, and the pump does not matter.

It will continue to push the fluid to overcome resistance as the pressure increases, even if this results in overload of the prime mover.